1. Field of the Invention
The present invention relates to a mobile communication system, and more particularly to a method for providing a mobile communication terminal with a private mobile communication service when the mobile communication terminal enters a private mobile communication network in a private mobile communication system interoperable with a public mobile communication network.
2. Description of the Related Art
Typically, a mobile communication network is classified into a public mobile communication network and a private (or office) mobile communication network, but it is impossible for the public mobile communication network to be interoperable with the private mobile communication network. That is, a mobile communication system is designed and implemented to enable only a public mobile communication service or only a private mobile communication service, so that a subscriber of a mobile communication terminal registered in a network can receive a communication service over a specific network with which the subscriber is registered.
Therefore, a subscriber of a mobile communication terminal registered in the public mobile communication network cannot receive a private mobile communication service, and a subscriber of a mobile communication terminal registered in a private mobile communication network cannot receive a public mobile communication service. As a result, it is necessary for a subscriber of a mobile communication terminal to receive a public mobile communication service and a private mobile communication service at the same time, using a single mobile communication terminal. In case of implementing a system for providing public and private mobile communication services at the same time, it is necessary for the system to determine whether a called party's call is a call generated from a public mobile communication network or a call generated from a private mobile communication network in case of a call termination.
Therefore, many developers are intensively conducting research into a new communication service method for enabling a subscriber of a mobile communication terminal registered in a public mobile communication network to receive a private mobile communication service along with a public mobile communication service. A representative example has been disclosed in Korean Patent Application No. 2000-028172, filed on 24 May 2000, by the same applicant as the present invention, and entitled “System for enabling Wireless Private Network Service by registering Public Network Mobile Communication Terminal in Office Wireless Private Network”, which is hereby incorporated by reference.
However, in the case where a mobile communication terminal registered in both a public mobile communication network and a private mobile communication network enters a zone of the private mobile communication network while using the public mobile communication network, it is difficult for a user of a mobile communication terminal to recognize the entrance into the zone of the private mobile communication network before recognizing whether he or she is in a public land mobile network area or in a private mobile communication network area.